package com.product.patch.util;
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import org.apache.commons.codec.binary.Base64;
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import org.apache.commons.io.IOUtils;
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import javax.crypto.Cipher;
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import java.io.ByteArrayOutputStream;
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import java.security.*;
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import java.security.interfaces.RSAPrivateKey;
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import java.security.interfaces.RSAPublicKey;
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import java.security.spec.InvalidKeySpecException;
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import java.security.spec.PKCS8EncodedKeySpec;
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import java.security.spec.X509EncodedKeySpec;
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import java.util.HashMap;
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import java.util.Map;
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public class RSAUtil {
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private static final String CHARSET = "utf-8";
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private static final String RSA_ALGORITHM = "RSA";
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public static Map<String, String> createKeys(int keySize){
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//为RSA算法创建一个KeyPairGenerator对象
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KeyPairGenerator kpg;
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try{
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kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
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}catch(NoSuchAlgorithmException e){
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throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
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}
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//初始化KeyPairGenerator对象,密钥长度
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kpg.initialize(keySize);
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//生成密匙对
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KeyPair keyPair = kpg.generateKeyPair();
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//得到公钥
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Key publicKey = keyPair.getPublic();
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String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());
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//得到私钥
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Key privateKey = keyPair.getPrivate();
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String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());
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Map<String, String> keyPairMap = new HashMap<String, String>();
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keyPairMap.put("publicKey", publicKeyStr);
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keyPairMap.put("privateKey", privateKeyStr);
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return keyPairMap;
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}
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/**
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* 得到公钥
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* @param publicKey 密钥字符串（经过base64编码）
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* @throws Exception
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*/
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public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
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//通过X509编码的Key指令获得公钥对象
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KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
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X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
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RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
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return key;
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}
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/**
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* 得到私钥
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* @param privateKey 密钥字符串（经过base64编码）
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* @throws Exception
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*/
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public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
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//通过PKCS#8编码的Key指令获得私钥对象
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KeyFactory keyFactory = KeyFactory.getInstance(RSA_ALGORITHM);
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PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
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RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
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return key;
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}
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/**
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* 公钥加密
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* @param data
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* @param publicKey
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* @return
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*/
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public static String publicEncrypt(String data, RSAPublicKey publicKey){
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try{
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Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
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cipher.init(Cipher.ENCRYPT_MODE, publicKey);
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return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), publicKey.getModulus().bitLength()));
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}catch(Exception e){
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throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
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}
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}
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/**
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* 私钥解密
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* @param data
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* @param privateKey
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* @return
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*/
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public static String privateDecrypt(String data, RSAPrivateKey privateKey){
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try{
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Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
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cipher.init(Cipher.DECRYPT_MODE, privateKey);
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return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), CHARSET);
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}catch(Exception e){
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throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
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}
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}
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/**
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* 私钥加密
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* @param data
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* @param privateKey
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* @return
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*/
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public static String privateEncrypt(String data, RSAPrivateKey privateKey){
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try{
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Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
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cipher.init(Cipher.ENCRYPT_MODE, privateKey);
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return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
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}catch(Exception e){
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throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
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}
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}
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/**
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* 公钥解密
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* @param data
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* @param publicKey
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* @return
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*/
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public static String publicDecrypt(String data, RSAPublicKey publicKey){
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try{
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Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
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cipher.init(Cipher.DECRYPT_MODE, publicKey);
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return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
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}catch(Exception e){
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throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
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}
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}
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private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize){
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int maxBlock = 0;
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if(opmode == Cipher.DECRYPT_MODE){
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maxBlock = keySize / 8;
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}else{
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maxBlock = keySize / 8 - 11;
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}
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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int offSet = 0;
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byte[] buff;
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int i = 0;
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try{
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while(datas.length > offSet){
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if(datas.length-offSet > maxBlock){
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buff = cipher.doFinal(datas, offSet, maxBlock);
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}else{
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buff = cipher.doFinal(datas, offSet, datas.length-offSet);
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}
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out.write(buff, 0, buff.length);
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i++;
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offSet = i * maxBlock;
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}
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}catch(Exception e){
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throw new RuntimeException("加解密阀值为["+maxBlock+"]的数据时发生异常", e);
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}
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byte[] resultDatas = out.toByteArray();
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IOUtils.closeQuietly(out);
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return resultDatas;
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}
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}
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